An Experimental and Numerical Study of Heat Transfer and Pressure Losses of V- and W-Shaped Ribs at High Reynolds Numbers

Abstract

An experimental and numerical investigation was conducted to assess the thermal performance of V- and W-shaped ribs in a rectangular channel. The ribs were located on one channel sidewall in order to simulate a typical combustor liner cooling. The cross section of the channel had an aspect ratio of 2:1. Local heat transfer coefficients were measured using the transient thermochromic liquid crystal technique. Pressure taps along the channel sidewall were used to obtain the periodic pressure losses. The rib height-to-hydraulic diameter ratio (e/Dh) was set to 0.02, and the rib pitch-to-height ratios (P/e) were 5 and 10. The Reynolds numbers investigated varied from 80,000 to 500,000. All rib configurations were additionally investigated numerically and the obtained computational results were compared with experimental data. For all computations the commercial software FLUENT™ was used with a two-layer k-ε turbulence model. It could be demonstrated that applying W-shaped ribs instead of V-shaped ribs has the advantage of an increased heat transfer enhancement, but is accompanied by a rise in pressure loss. Reducing the rib pitch-to-height ratio from 10 to 5 decreases the heat transfer enhancement, but results in a significantly reduced pressure loss. Finally, the best thermal performance was found for W-shaped ribs with a pitch-to-height ratio of 10, having a slightly increased pressure loss but with considerable rise in heat transfer enhancement compared to V-shaped ribs.

Modelling of Convective Heat and Mass Transfer in Rotating Flows

“…CENTAUR ® software [52] (see also Sect. 8.2) confirmed also by [16,57], etc. A grid-independency investigation carried out using a coarse mesh of *1.1 million cells, a medium mesh of 1.9 million cells, a finer mesh of 3.2 million cells, and a very fine mesh of 3.65 million to 3.91 million cells revealed that namely the very fine mesh ensured the sufficient near-wall grid resolution and grid independency for the ribbed channel, while for the smooth channel a grid with 1.15-1.3 million cells was needed.…”

“…In experiments [57] on a rough disk, the onset of transition to turbulence began at Re ω = (0.23-1.23) × 10 5 (on a smooth disk, at Re ω = (2.4-2.63 × 10 5 ). The boundary of the end of transition also shifted down to Re ω = 2.55 × 10 5 on a rough disk in comparison with Re ω = 3.4 × 10 5 on the smooth disk in [58].…”

Convective heat transfer enhancement in solar air channels

“…The overall thermal performance was found to be better for the discrete V-shaped and discrete W-shaped ribs in comparison to continuous V-and Wshaped ribs. Maurer et al [86] investigated the thermal performance of V-shaped and W-shaped ribs provided on one side or both sides of a test channel for an Re range of 80,000e500,000. The W-shaped ribs were found to have better heat transfer and pressure drop.…”

A Review of Heat Transfer and Pressure Loss Characteristics Through Convective Cooling Method for Gas Turbine Thermal Management

“…V-shaped ribs show a higher thermal performance than angled ribs. Similar comparative analysis was conducted by [9] experimentally and numerically to examine the thermal performance of V-shaped and W-shaped ribs in a rectangular channel with an aspect ratio of 2:1. The blockage ratio (e/D h ) was 0.02; the rib pitch-to-height ratios (P/e) were 5 and 10 and the tests were performed for Reynolds numbers between 80,000 to 500,000.…”